More attention is drawn nowadays in worldwide practice to various techniques for reliably joining a diversity of structural elements made of concrete, reinforced concrete, metal, or glass.
Currently, there are quite a number of methods and techniques for joining together a variety of constructions in industrial, civil, and hydraulic construction engineering, as well as in road building.
A particular concern in these methods is the joint between the surfaces being joined together for which strict requirements are imposed for adhesive bond and water-tightness. Such joints may behave differently during operation and, are therefore, classified as flexible and rigid joints. Rigid joints are usually made by welding, e.g., steel inserts, or connecting reinforcement bars, or some other joinable elements of parts to be joined together, followed by tightening the joints are usually made by welding, concrete, or by bonding together the concrete surfaces being joined using polymer solutions. Flexible joints are usually made with the use of a metal or rubber stress compensator with its ends embedded into the construction members to be joined together and by a variety of polymer and bituminous sealing compounds.
However, joints made in such a way are too complicated in construction, hard-to-make, and may be water-permeable and liable to fail when exposed to impact loads.
Joined construction structures for use in underground transport construction engineering for water- and corrosion-proofing of industrial wastewater treatment facilities and in hydraulic construction engineering should possess, apart from mechanical strength, reliable water-tightness.
Constructional structures that leak water at their joints are liable to rapidly destruct, which involves enormous expenditures afterwards for repair-and-restoration work. When corrosive fluids are involved, which is the case for treatment facilities, environmental pollution is liable to occur as a result of failure of such facilities.
Known in current practice is the use of solutions for water-tighting of reinforced concrete structures. Such solutions incorporate standard portland cement, a self-stressing or self-expanding cement, an aggregate, and water. However, use of cements featuring high expansion- and self-stressing ratio has demonstrated that a considerable amount of stresses are liable to arise in the joint during the curing process, resulting in spalling and splitting of the material of the construction structures being joined together.
A similar joining practice is performed by a known quick-to-set sealing mixture, consisting of gypsum-aluminous expanding cement, aluminous cement, portland cement, chrysotile asbestos, and water. However, the fact that chrysotile asbestos, which is known to be a carcinogen, is used as a reinforcing material renders such mixture instable and impracticable.
Use of diverse superplasticiers is known to improve the features of diverse concrete mixes.
As it has previously been stated, flexibility of joints between constructions and structures is attained due to the use of a variety of sealing compounds applied to the joining surfaces of the structural elements. In particular, such sealing compounds are based on various rubbers, such as polyisobutylene rubber, butyl- and thickol rubbers.
For a combination of the features, a special concern in sealing compounds is whether compositions is based on liquid thiokols or liquid polysulfide rubbers. These are essentially oligomers which, after having been exposed to vulcanization, turn out to be cross-linked polymers, thus forming elastic products featuring good physico-mechanical, adhesive, and dielectric characteristics as well as high elasticity in a temperature range minus 60 to plus 90.degree.-110.degree. C.
Known in the art is a method for producing cast-in-place flexible joined-together constructional structures comprising a 0.5-2.0 mm thick layer of a mixture applied to the surfaces of the elements of the constructional structures to be joined together. Such mixture incorporates liquid thiokol (in combination with epoxy resin and pigments) (54-65.2 wt. %), a curing agent taken in an amount of 0.12-7.90 wt. % and appearing as a mixture of sodium bichromate, kaolin, diphenylquanidine, and water, coal tar (0.2-43.3 wt. %), and solvents. A space between the joining surfaces is immediately filled with a cement mortar having the following components (wt. %):
______________________________________ cement based on aluminous slags and having a 29.9-30.7 maximum expansion ration of 0.3% mortar sand 59.80-60-03 water 7.7-9.6 plasticizer (optional) 0.1-0.2 hardener (SU A, 1,765,434, optional) 0.75 ______________________________________
After having been cured for a seven-day period sufficient for concrete hardening, the joined-together constructional structures acquire monolithic-and-elastic properties, and their joints retain strength and water-tightness after repeated exposure to transverse tensile and compression loads (5000 cycles on the average) as well as heating and cooling procedures.
However, such a method for producing cast-in-place flexible joints of constructional structures is too complicated for practical applications. This is because even an insignificant deviation from the formulation of the compound based on liquid thiokol and failure to observe the strict requirement as to the immediate and thorough homogenization of all components of the compound can result in disturbing the vulcanization process. The result of such a disturbance of the thiokol vulcanization process makes it impossible for a reliable adhesion of the surfaces being joined together under conditions of variable loads acting upon the joint material, more specifically, the cement stone. The resultant joint possesses neither strength nor flexibility. Apart from what has been discussed above, the known method under discussion involves an immediate application of the thiokol-based composition just after its preparation and thorough agitation. Thus, the fact that the vulcanization process occurs immediately after intermixing of the components prevents preliminary preparation of the composition.
The present invention has as its primary and essential object to provide a method for producing cast-in-place flexible joined-together constructional structures and buildings suitable for successful use in industrial construction engineering and reconditioning of constructions and buildings by providing a stable and reliable adhesion of the material of the structures being joined together to the joining material under conditions of variable loads and corrosive media.